An inspection into the class of bis(alkyne)-undecacarbonyl- quadro-tetraruthenium complexes. Crystal structure and dynamic behaviour of Ru 4(CO) 11 (μ 4, η 2-MeC 2Ph) 2

Abstract

The reactions of the butterfly complex Ru 4(CO) 12(MeC 2Ph) with several alkynes give the quasiplanar derivatives Ru 4(CO) 11(MeC 2Ph)(Alkyne) in almost quantitative yields. The structure of Ru 4(CO) 11(MeC 2Ph) 2 has been determined by X-ray methods. Crystals are monoclinic, space group C2/c, with Z = 4 in a unit cell of dimensions a 22.383(16), b 9.048(8), c 18.268(12) Å, β = 127.25(4)°. The structure has been solved from diffractometer data by Patterson and Fourier methods and refined by full-matrix least-squares to R = 0.034 for 1420 observed reflections. The complex, having an imposed C 2 symmetry, presents a tetranuclear metal cluster in which the Ru atoms are in a tetrahedrally-distorted square arrangement. Ten carbonyls are terminal and one symmetrically bridges an edge of the cluster. Each of the two alkyne ligands is σ-bonded to two Ru atoms on the opposite vertices of the cluster and π-bonded to the other two. The organometallic cluster has a Ru 4C 4 core in which the metal and carbon atoms occupy the vertices of a triangulated dodecahedron.